| Titles |
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English :
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Genetic study on milk productive traits using first lactation records
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| Abstract |
Totals of 1689 first lactation records of Friesian cows were used in the present study. Number of sires and the average number of daughters per sire (k) were 240 and 6.4, respectively. These data were used to estimate genetic and phenotypic parameters for total milk yield (TMY), 305-day milk yield (305-DMY), lactation period (LP) and productive efficiency (PE). The statistical model included the effect of sire as random effect, season and year of calving as fixed effects and both age at first calving (AFC) and weight at calving (WC) as covariate on milk production traits. The arethmatic means of TMY, 305-DMY, PE and LP were 3681,3181,2.79 kg and 338 d, respectively. Season of calving had significant (P<0.01) effect on 305-DMY. Whereas it had non-significant effects on the other studied traits. Year of calving had a highly significant (P < 0.001) effect on the different studied traits except for LP the effect was not significant. Estimates of partial linear regression coefficients of TMY and 305DMY on AFC and WC were highly significant (P <0.01or 0.001). Estimates of partial quadratic regression coefficients of all studied traits on AFC and/or WC were not significant. Sire of heifers had a highly significant (P < 0.001) effect on all traits studied except for LP. The sire variance component б2 is ranged between 3.32 to 12.7% of the total variance for all milk production studied traits. Heritability estimates (±S.E) for TMY, 305-DMY, PE and LP were 0.420 ±0.083, 0.513± 0.088, 0.385 ± 0.082 and 0.133 ± 0.068, respectively. Highly positive and significant genetic and phenotypic correlations were found among the different studied traits.
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| Publication year |
2000
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| Pages |
73-79
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| Availability location |
معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
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| Availability number |
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| Organization Name |
Animal Production Research Institute (APRI)
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| City |
الاسكندرية
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| serial title |
Proceeding 3rd All Africa conference Animal Agricultural &11th conference Egyptian society Animal Proceeding Alexandria, Egypt,
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| Author(s) from ARC |
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| External authors (outside ARC) |
السعيد ذهدى عودة
جامعة المنصورة
ناظم عبد الرحمن شلبى
جامعة المنصورة
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| Agris Categories |
Animal husbandry
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AGROVOC
TERMS |
Genetic parameters.
Lactation.
Milk.
Milk production.
Milk yield.
Phenotypes.
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| Proposed Agrovoc |
productive efficiency;
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| Publication Type |
Conference/Workshop
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